We propose to investigate the impact of the built environment characteristics on body size, physical activity and diet in residents of New York City (NYC). We will use data from three large human health studies. The first data set will be from 1000 Black and Hispanic children enrolled in prospective cohort study of Head Start families. From all of the children we will have complete demographic data, and mother's reports on the height and weight and physical activity of the child. From 500 of the children data will be available on skin fold thickness, body mass index (BMI) and 6 days of physical activity monitoring. Data will be available at baseline and from two annual follow-ups of the cohort. The second data set will be from 18,000 adult New Yorkers from whom we will have demographic data and objectively measured BMI. The third will be from 2,400 healthy Black and Caucasian. From these women we will have demographic data, questionniare data on diet and physical activity and objective measures of BMI, waist and hip circumference and body fat by bio-impedence. From all of these subjects we will have a home address which we will geocode into a CIS model of New York City. Multi-level modeling approaches will be used to determine whether neighborhoods characterisitcs (for example;land use, street design, availability and quality of parks and retail food stores, zoning, public transport, farmers markets) predict body size, physical activity and diet. Because of the very large immigrant population in NYC we will conduct qualitative research on how acculturation to the built environment of NYC impacts body size. Prior work suggests that acculturation to main stream American norms leads to weight increases in immigrants and their children. We do not see this effect in our data and propose that NYC is not "main stream America". We propose to conduct qualitative research on Hispanic mothers and children in the Head Start study and investigate how they relate to the built environment of NYC. Our goal is to develop a new measure of acculturation that includes adaption to the built environment of NYC and will be useful in studies of obesity. The quantitative research will also be used to develop new GIS based measures of aspects of the City that are important to the mothers. This research on the phsyical environment and adaption to it, will identify strategies for building and organizing communites that increase physical activity, improve diets and reduce obesity.